Effects of interaction of nitrogen and sulfur on seedling growth,uptake and utilization of nitrogen and sulfur of winter wheatunder high nitrogen conditions

The effects of interaction between nitrogen and sulfur fertilization on seedling growth, uptake and utilization of nitrogen and sulfur of winter wheat were studied in hydroponic conditions. The results show that under the same nitrogen level, the activities of wheat root are decreased significantly in the levels of sulfur from 0.15 mmol/L to 2.40 mmol/L. Under the 4 mmol/L of nitrogen level, the contents of sulfur and nitrogen in shoots of seedlings are increased with the increase of S levels, the photosynthetic rates of leaves are increased, the development of leaves and secondary roots are promoted, and the dry matter accumulations in shoots and roots are increased, while the use efficiencies of sulfur and conducive to the development of seedlings, and the accumulations of dry nitrogen are decreased. Under the 8 mmol/L of nitrogen level, the sulfur contents of wheat shoots are increased with the increase of S levels, while there are not significant changes in the nitrogen contents, and the excessive sulfur application can result in the reduce of the ability of photosynthesis. It is also not matter and nitrogen and sulfur in shoots and roots. Under the 0.15 mmol/L of sulfur level, it is conducive to improve the contents of nitrogen in shoots and roots with the increase of nitrogen levels. Under the 2.40 mmol/L of sulfur level, there are no significant differences in the contents of nitrogen in shoots and roots. These results indicate that at certain levels of nitrogen and sulfur application, there is mutual promotion between nitrogen and sulfur, at too high levels of nitrogen and sulfur application, there is mutual inhibition between them, which is not conducive to the absorptions and uses of nitrogen and sulfur in wheat. The responses of different cultivars to the nitrogen and sulfur fertilization are different. Under the 4 mmol/L nitrogen level, higher level of sulfur is more conducive to the accumulations of sulfur and nitrogen in different organs of Yumai 34 and Zimai 12 compared to those of Lumai 21 and Yannong 19, and under the 8 mmol/L nitrogen level, the tolerance abilities of Yumai 34 and Zimai 12 against excessive sulfur are higher.